Contrasting impacts of two-type El Ni?o over the western North Pacific during boreal autumn

摘要

This work contrasts the climatic impacts of so-called warm-pool (WP) and cold-tongue (CT) El Ni?o on the atmo- spheric circulation over the western North Pacific (WNP). It is found that the anomalous atmospheric circulation over the WNP is nearly opposite in response to these two types of El Ni?o events in developing autumn. A weak anomalous anticyclone appears over the WNP during CT El Ni?o, whereas a weak anomalous cyclone emerges in the same region during WP El Ni?o. These nearly opposite autumn responses of atmospheric circulation have a significant impact on East Asian climate, and southern China autumn rainfall in particular, although this contrast tends to diminish as El Ni?o events enter their mature phase.